The present invention relates generally to the field of electronic data storage and retrieval, and in particular to an improved writer in a merged giant magnetoresistance (GMR) read/write head.
A GMR read/write head generally consists of two portions, a writer portion for storing magnetically-encoded information on a magnetic disc and a reader portion for retrieving magnetically-encoded information from the disc. The reader portion typically consists of a bottom shield, a top shield, and a giant magnetoresistive (GMR) sensor positioned between the bottom and top shields. Magnetic flux from the surface of the disc causes rotation of the magnetization vector of a free layer of the GMR sensor, which in turn causes a change in electrical resistivity of the GMR sensor. The change in resistivity of the GMR sensor can be detected by passing a current through the GMR sensor and measuring a voltage across the GMR sensor. External circuitry then converts the voltage information into an appropriate format and manipulates that information as necessary.
The writer portion typically consists of a top and a bottom pole, which are separated from each other at an air bearing surface of the writer by a gap layer, and which are connected to each other at a region distal from the air bearing surface by a back gap closer or back via. Positioned between the top and bottom poles are one or more layers of conductive coils encapsulated by insulating layers. The writer portion and the reader portion are often arranged in a merged configuration in which a shared pole serves as both the top shield in the reader portion and the bottom pole in the writer portion.
To write data to the magnetic media, an electrical current is caused to flow through the conductive coils to thereby induce a magnetic field across the write gap between the top and bottom poles. By reversing the, polarity of the current through the coils, the polarity of the data written to the magnetic media is also reversed. Because the top pole is generally the trailing pole of the top and bottom poles, the top pole is used to physically write the data to the magnetic media. Accordingly, it is the top pole that defines the track width of the written data. More specifically, the track width is defined by the width of the top pole at the air bearing surface.
Prior art configurations have a distinct limitation in that the top pole is typically formed over a mound of coils, resulting in the top pole having a xe2x80x9cbumpxe2x80x9d shape. The portion of the top pole adjacent the air bearing surface in prior art configurations is sloped. It is therefore difficult to precisely control the width of the top pole at the air bearing surface, particularly as the width necessarily becomes smaller to allow for greater data storage densities. Commonly assigned and co-pending provisional application No. 60/144,269, entitled xe2x80x9cHIGH FREQUENCY RESPONSE WRITER WITH RECESSED SP AND TORROIDAL COILSxe2x80x9d, filed on Jul. 15, 1999, discloses an improved write head with a vertical coil configuration, wherein the bottom coil layer is embedded within a recess of the shared pole. By positioning the bottom coil layer in a recess in the shared pole, a substantially planar top pole may be formed.
In addition to positioning the coil in a recess in the shared pole as disclosed in provisional application No. 60/144,269, further improvements are desirable to produce a substantially planar top pole, and thereby allow for greater tolerance control of the width of the top pole at the air bearing surface.
The present invention is a magnetic recording head having an air bearing surface. The magnetic recording head includes first and second top poles, a bottom pole, a write gap layer positioned between the first top pole and the bottom pole, a first conductive coil positioned between the second top pole and the write gap layer, and a second conductive coil positioned in a recess of the bottom pole. At least a portion of the second conductive coil is positioned near the air bearing surface under the first top pole. In addition, the recess of the bottom pole is defined by a magnetic sublayer, wherein an inner surface of the magnetic sublayer does not include sharp corners near the air bearing surface.